The invention relates to well treatments involving temporarily decreasing the permeabilities of subterranean earth formations.
Various process, such as working over a well, diverting injected fluids, extending and/or acidizing a fracture, or the like, can be facilitated by temporarily plugging permeable subterranean earth formations. U.S. Pat. Nos. 3,615,794 and 3,766,984 describe compositions and procedures for effecting such temporary pluggings by injecting significantly basic aqueous suspensions of a galactomannan which has been treated to delay the rate of its hydration, a buffering agent, and a cross-linking and hydrating agent for temporarily gelling the gum. Those patents mention several difficulties which are involved in using such cross-linked gums and indicate that the patented processes avoid various difficulties; other than those due to the tendency for such cross-linked gums to fail to break down to provide a low viscosity within a selected period of time.